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Congenital Disorders of Glycosylation (CDG) Type II: A Complex Metabolic Disorder

CDG Type II is a subtype of Congenital Disorders of Glycosylation, a rare genetic metabolic disorder. This condition affects the processing of glycans, specifically the trimming or remodeling of oligosaccharide building blocks attached to proteins.

Characteristics and Symptoms

• Muscle weakness
• Short stature
• Cleft palate
• Blood clotting problems
• Liver disease

These symptoms may vary depending on the specific genetic defect affecting glycosylation. CDG Type II is characterized by defects in the processing of glycans, which can lead to a range of clinical manifestations.

Types of CDG Type II

CDG Type II includes several subtypes, such as: * N-linked type II forms of CDG + Genetic defects that affect the trimming or remodeling of oligosaccharide building blocks once they are attached to proteins

Some specific types of CDG Type II include: * PGM1-CDG: Symptoms may include muscle

Based on the available information, the symptoms of Congenital Disorder of Glycosylation Type II (CDG II) can vary in severity from mild to severe, disabling or life-threatening. Some common signs and symptoms include:

• Developmental delays
• Imbalance
• Muscle weakness
• Nerve damage
• Seizures
• Low muscle tone or floppiness (hypotonia)
• Abnormally small head (microcephaly)
• Scaly skin
• Failure to thrive

It's worth noting that the symptoms and severity of CDG II can vary from child to child, and some individuals may experience a broader range of symptoms.

According to [2], CDG can be associated with a broad variety of symptoms and can vary in severity. This suggests that the symptoms of CDG II are not limited to those listed above, but rather can include a wide range of manifestations.

Additionally, [8] notes that CDG typically present with multi-systemic manifestations, most commonly developmental delay, failure to thrive, hypotonia, neurologic abnormalities, hepatopathy, and others. This further emphasizes the complexity and variability of symptoms associated with CDG II.

References: [2] May 11, 2021 — CDG can be associated with a broad variety of symptoms and can vary in severity from mild to severe, disabling or life-threatening. [8] by IJ Chang · 2018 · Cited by 247 — CDG typically present with multi-systemic manifestations, most commonly developmental delay, failure to thrive, hypotonia, neurologic abnormalities, hepatopathy...

Diagnostic Tests for Congenital Disorder of Glycosylation Type II (CDG II)

Congenital disorders of glycosylation (CDGs) are a group of rare genetic disorders that affect the body's ability to synthesize glycans, which are complex carbohydrates essential for various cellular processes. CDG II is a subtype of CDG that affects the synthesis of N-glycans.

Clinical Testing

When a diagnosis of CDG II is suspected based on symptoms, a detailed patient history, and a thorough examination, clinical testing is needed to confirm the condition [1]. The recommended first-tier test to screen for congenital disorders of glycosylation (CDG) is a biochemical test that analyzes transferrin and apolipoprotein C-III [8].

Biochemical Tests

A simple blood test can help diagnose or confirm CDG II by analyzing the glycosylation status of transferrin, which is a protein involved in iron transport [4]. This test is useful for diagnosing patients with clinical symptoms consistent with CDG II.

Molecular Testing

The diagnosis of PMM2-CDG or MPI-CDG, which are subtypes of CDG II, is confirmed through molecular testing showing biallelic pathogenic variants in PMM2 or MPI, followed by PMM or MPI enzyme activity analysis [7].

Comprehensive N-glycan Testing

CHOP offers comprehensive N-glycan testing to help diagnose congenital disorders of glycosylation (CDGs), including CDG II. This testing is used to screen patients for suspected CDG II.

In summary, the diagnostic tests for CDG II include:

• Biochemical tests analyzing transferrin and apolipoprotein C-III
• Molecular testing showing biallelic pathogenic variants in PMM2 or MPI
• Comprehensive N-glycan testing offered by CHOP

References: [1] - [9] (citations correspond to the numbers in the context block)

Treatment Options for Congenital Disorder of Glycosylation Type II (CDG-II)

Congenital Disorder of Glycosylation Type II (CDG-II), also known as PMM2-CDG, is a rare genetic disorder that affects the body's ability to properly glycosylate proteins. While there is no cure for CDG-II, various treatment options can help manage its symptoms and improve quality of life.

• Oral Mannose Supplementation: This has been shown to be effective in restoring glycosylation in patients with PMM2-CDG [8]. Oral mannose supplementation therapy was the first therapeutic approach for this condition, and it successfully restored glycosylation in patients' cells.
• Supportive Care: Treatment for most types of CDG is largely supportive, with a focus on managing symptoms and preventing complications. This may include occupational therapy, speech therapy, physical therapy, and other forms of rehabilitation to help individuals with CDG-II develop their skills and abilities [9].
• Gene Therapy: Research into gene therapy holds promise for the treatment of CDG-II in the future. Gene therapy involves replacing or repairing a faulty gene that is causing the disorder.
• Dietary Interventions: Dietary interventions, such as a diet rich in mannose, may also be beneficial in managing symptoms and improving quality of life.

It's essential to note that each individual with CDG-II may respond differently to these treatment options. A healthcare professional should be consulted for personalized advice on the best course of treatment.

References:

[8] Monticelli M et al. (2023) Oral mannose supplementation therapy was the first therapeutic approach for the PMM2-CDG, as it successfully restored glycosylation in patients' cells [citation 8].

[9] Most types of CDG affect the nervous system, causing developmental delays. Starting

Understanding Congenital Disorder of Glycosylation Type II (CDG-II)

Congenital disorders of glycosylation (CDGs) are a group of rare genetic diseases characterized by defects in the synthesis of oligosaccharides. CDG-II, also known as PMM2-CDG, is one of the most common types of CDG.

Differential Diagnosis

The differential diagnosis for CDG-II involves considering various symptoms and clinical manifestations that may be present in affected individuals. Some of these include:

• Increased infectious susceptibility: Individuals with CDG-II are more susceptible to infections due to impaired immune function.
• Marked leukocytosis: Elevated white blood cell counts can be a characteristic feature of CDG-II.
• Rare Bombay blood group: The presence of the rare Bombay blood group is associated with CDG-II.
• Severe mental retardation: Individuals with CDG-II may exhibit severe intellectual disability.
• Short stature: Affected individuals often have short stature.

Clinical Stages

CDG-II can be divided into three clinical stages:

1. Infantile multisystem stage: Characterized by increased infectious susceptibility and marked leukocytosis.
2. Late-infantile and childhood ataxia–intellectual disability stage: Affected individuals may exhibit severe intellectual disability, short stature, and ataxia (loss of coordination).
3. Adult stable disability stage: Individuals with CDG-II in this stage may experience a more stable course of the disease, but still have significant disabilities.

References

• [1] Congenital disorders of glycosylation (CDGs) are a group of over 100 monogenic human diseases with defects in the synthesis of oligosaccharides. Oligosaccharides, or glycans, are multisugar structures attached to proteins or lipids.
• [4] PMM2-CDG, the most common of a group of disorders of abnormal glycosylation of N-linked oligosaccharides, is divided into three clinical stages.
• [14] PMM2-CDG, the most common of a group of disorders of abnormal glycosylation of N-linked oligosaccharides, is divided into three clinical stages: infantile multisystem, late-infantile and childhood ataxia–intellectual disability, and adult stable disability.

Note: The references provided are based on the search results and may not be an exhaustive list of all relevant studies or publications.